Before experiment, the sediment was spiked with 20 mg/kg (dry basis) of each of phenanthrene and
anthracene by addition of PAH standard solution (1000 mg/L in acetone-phenanthrene/anthracene). After
acetone was volatized in fuming cupboard, the sediment were well mixed with different additives, i.e.
NaN3, Tween 80, Os, SA, SL and SMC respectively (Table 2), and the moisture contents of mixtures
were adjusted to 30±0.5%. After the headspaces were